In reply to Mr_Yeti:
I brought a pair at the outdoor show for £75, usually £90. They need to fit snug, they look weird but are supposed to be good for you, as you begin to use muscles in your feet and ankle that aren't normally used. I was told that people run in them (people have run marathons in them) but I can't believe that that's not bad for your knees. I saw somone using them at the climbing wall too, it must give you strong toes! Pretty cool though, and they'll replace them if they start to fall apart withn two years.
find them on www.primallifestyle.com
Be prepared for weird looks though!